1. Field of the Invention
The present invention relates to an image forming device such as photocopiers, printers, facsimiles, or combined machines of the foregoing ones, and a fixing device mounted on the image forming device.
2. Description of the Related Art
There has been known fixing devices mounted on image forming devices, such as photocopiers and printers, that have a short warm-up time and a short first print time, and are less prone to cause a fixing error even if the devices are operated at a higher speed (for example, refer to Japanese Patent Application Laid-open No. 2010-96782).
Specifically, the fixing device shown in FIGS. 2, 4, and others of Japanese Patent Application Laid-open No. 2010-96782 is formed by a fixing belt (reference numeral 21); a pipe-like heating member fixedly provided so as to be opposed to an inner peripheral surface of the fixing belt except for a nip portion (reference numeral 22); a heater (reference numeral 25) provided inside the heating member for heating of the heating member; a stationary member (reference numeral 26) provided inside the fixing belt to contact under pressure a pressing roller (reference numeral 31) via the fixing belt to form the nip portion; an approximately plate-like reinforcement member (reference numeral 23) that contacts the stationary member for reinforcement of the stationary member, and the like. The approximately plate-like reinforcement member has a relatively narrow width (along a direction of conveyance) so as to abut a part of a surface of the stationary member.
In addition, when the fixing belt is heated by the pipe-like heating member heated by the heater, a toner image on a recording medium conveyed toward the nip portion, is fixed on the recording medium under heat and pressure at the nip portion.
Since the foregoing fixing device of Japanese Patent Application Laid-open No. 2010-96782 is mounted by fitting the stationary member into a concave portion of the pipe-like heating member, a contact area (contact width) of the reinforcement member with respect to the stationary member is small. However, even if the stationary member is subjected to a force from the reinforcement member in an unbalanced manner, the stationary member does not fall down due to the unbalanced force.
Meanwhile, the fixing device of Japanese Patent Application Laid-open No. 2010-96782 or the like may be configured, for the purposes of further improvement in heating efficiency of the fixing belt, reduction in cost and size of the fixing device and the like, such that the pipe-like heating member is eliminated and the fixing belt is heated directly by a heating unit with no intervention of the pipe-like heating member.
In this case, however, since there is no heating member (concave portion) for preventing falling of the stationary member, the stationary member in contact under pressure with the reinforcement member cannot be held in a well-balanced manner and thus may fall down. If the stationary member falls down, a desired nip cannot be formed, which leads to a fixing error on an output image or a conveyance error of a recording medium.
There are needs to solve the foregoing problem and to provide a fixing device that has a short warm-up time and a short first print time, does not cause a fixing error or the like even if the device is operated at a higher speed, and does not allow the stationary member in contact under pressure with the reinforcement member to fall down, and an image forming device.